This invention relates to a destacker in which each one of a multiplicity of blank sheet materials piled one on another as a stack on a pallet disposed at a predetermined position within the destacker is lifted by means of a plurality of vertically movable vacuum cups and transported by means of a conveyor to a machining apparatus such as, for example, a press.
In general, in the conveyance of sheet materials by using a destacker, when all the sheet materials on a pallet carried to a predetermined position inside the destacker have been supplied for a machining process, it is necessary to take the empty pallet out from the destacker and carry out a stack supply operation wherein a new pallet loaded with a stack consisting of a plurality of sheet materials is carried into the destacker.
In the case of well-known conventional types of destackers, the above-mentioned stack replenishing operation requires a long time, and the conveyance of sheet materials is suspended during the replenishment of the stack. As a result, the continuous supply of the sheet materials to a press is interrupted, and also suspension of the press operation takes place unavoidably, during the period, thus giving rise to a reduction in the operating rate of the press.